The present invention relates to a ring expander device, and more particularly to a device for expanding a ring-like support to increase the diameter thereof.
It is desirable to segregate sanitary or sewerage systems from those systems designed to handle storm and drainage water since such segregation reduces an unnecessary burden on the sewerage treatment facility. Obviously, when drainage and storm water empties into a sanitary system the sewerage treatment plant must necessarily handle and treat the storm water in addition to the sewerage material. Standard frames and covers for manholes that lead to sanitary or sewerage systems generally include heavy cover constructions with passageways therein that serve to vent the overall system for the purpose of relieving internal pressure as well as vacuum build-ups. The passageways in these manhole covers also enable storm water to empty into the sewerage system. It is impossible to simply seal off or otherwise eliminate the cover passageways since pressure developed within the sewerage system could easily produce a force sufficient to blow the cover away from its seated position at the manhole opening or blast the plugs away from the passageways. Additionally, pressure developed within the sewerage system can easily cause damage to the system if that pressure is not relieved.
Application Ser. No. 524,537, filed Nov. 18, 1974, describes a support ring for mounting a manhole closure assembly within a manhole opening. When installed the closure assembly functions to prevent storm water from entering the manhole and also relieves internal pressure therein when it exceeds a predetermined amount. The description of the support ring together with the remaining specification of the above application is herewith incorporated in the present application.
While most manholes include openings surrounded by an annular manhole frame that includes several inwardly directed flanges, a significant number of manhole frames do not include an appropriate flange for supporting the manhole closure assembly. The absence of such flange structure on the manhole frame necessitates a separate support for the closure assembly. The device of the present invention is used to expand the support ring into position within a manhole opening where it serves as a mounting for the closure.